In a yarn storage and feed device described in DE-A1-37 34 284, the threading device comprises direction-jet nozzles and air guidance surfaces. In case of yarn breakage, the free yarn end of the broken yarn or of a spare yarn is moved by activating all direction-jet nozzles from the inlet into the yarn storage and feed device through the winding element and then along a detour path as compared with the normal yarn path along the storage drum into the guide opening, for instance, when the drive is stopped in a predetermined position. In case of partial failure with yarn breakage between the inlet and the storage drum, one ignores the fact that a regular yarn supply from which the yarn runs correctly into the guide opening might still be present on the storage drum. Unnecessary and time-consuming extra work is performed during the threading operation, for continuous threading is only required in case of total failure with yarn breakage where the yarn stored on the storage drum has also been consumed.
In a yarn storage and feed device described in EP 0 420 176, a first direction-jet nozzle assembly that has simultaneously supplied thereto two identical threads is provided in the inlet. At least one additional direction-jet nozzle is provided between the outlet of the winding element and the guide opening. Irrespective as to whether after yarn breakage there is a partial failure in which yarn is still stored on the storage surface or whether there is total failure in the case of which the yarn stored on the storage surface has been consumed after yarn breakage, both free yarn ends of the broken one yarn are eliminated in case of failure and the other yarn is newly threaded subsequently. To eliminate yarn possibly still stored on the storage surface, the winding element is turned back and the yarn is sucked back and discharged from the first direction-jet nozzle assembly.
In a yarn storage and feed device described in EP 0 269 140, partial failure caused by yarn breakage between the reel and storage drum with at least partly correct yarn supply on the storage drum is solely remedied in an automatic way. An auxiliary nozzle moves the yarn end of the broken yarn or of a spare yarn into the inlet of the yarn storage and feed device and up to the outlet of the winding element. A cutting device separates an initial part of the yarn supply on the storage drum to create a free yarn end at this place. Suction air nozzles suck in both yarn ends before a splicer connects the yarn ends. This principle presupposes an operation control device that quickly responds to yarn breakage. The threading device is not capable of eliminating total failure with an empty storage drum.